1. ## d20 made into d6 or d10

Note: This is not for epic-level play.

So someone showed me a d6 variant to replace the d20 system:
http://www.systemreferencedocuments....thedRolls.html

However, it is missing the fact that you still roll everything from d2 to d12 with weapons and magic so I thought I'd offer a conversion table. Simply roll a d6 instead of the old die and add a bonus/penalty per die rolled accordingly:
1 | 1
1d2 | 1d6/3
1d3 | 1d6/2
1d4 | 2d6/3
1d8 | 4d6/3
1d10 | 5d6/3
1d12 | 2d6
3d2 | 1d6
3d4 | 2d6
3d8 | 4d6
3d10 | 5d6[/table]

Anytime there are multiple dice, look for the highest amount possible before looking at the lower calculations.

For example, if a character had an effect which dealt 4d4 damage, they would look at 3d4 conversion (being the highest point of d4s) and roll 2d6. They would then look at the remaining 1d4 and roll another 2d6 and divide that second roll by 3.

d10
Also, the system could be converted into a d10 system as follows:
Bonuses and penalties apply to reducing a character's number of d10s. A Strength modifier of +4, for example, adds 4d10 to melee attack rolls and melee damage rolls.

1 or d2| 1d10
1d3 or d4 | 2d10
1d6 | 3d10
1d8 | 4d10
1d10 | 5d10
1d12 | 6d10
1d20 | 10d10
[/table]
1 = -1 success
2-5 = 0 succeses
6-9 = +1 success
10 = +2 successes

For every 10d10 a character would normally roll, do not bother rolling dice and instead assume it is automatically 5 successes. Doing this should never allow a character to roll less than 1d10 when attempting something.

Everything with a DC would be divided by 2 rounded appropriately to the nearest number and that is the number of successes necessary to accomplish the task. Same goes for a character's AC.

I honestly have no idea why anyone would want to do this since d20 systems are obviously better *hint of bias* but I just thought it'd be a neat possibility.

2. ## Re: d20 made into d6 or d10

I think you're approaching it wrong.

1 = 1. No dice involved there.
1d2 can be generated off of a d6, so why bother?
1d3 is also generated off of a d6, so why bother?
1d4 is equivalent to 1d6-1; 1d6-2 has a much lower average than 1d4. 1d6-1 has an average of 2.66, while 1d4 has an average of 2.5. 1d6-2 has an average of 2, which is far below 2.5; I'd shoot a bit high over a bit low.
1d8 is equivalent to 1d6+1; both have the exact same average (4.5).
1d10 should probably be 2d6-1; that gives an average of 6 rather than 5.5, but that's probably fine.

3. ## Re: d20 made into d6 or d10

1d1 = 1
1d2 = (1d6) / 3
1d3 = (1d6) / 2
1d4 = 1d8 or (2d6) / 3
1d6 = 1d6
1d8 = 1d8 or (4d6) / 3
1d10 = (5d6) / 3
1d20 = (10d6) / 3

Just roll an appropriate amount of times and divide. Pretty simple, but it's just a lot easier to roll with actual dice, and not just a d6.

4. ## Re: d20 made into d6 or d10

Hmm, that works too.

These really didn't have much purpose. I have several friends who prefer d6 and d10 systems and just thought the option of converting would be helpful for those that like D&D-like genres but prefer other dice systems.

5. ## Re: d20 made into d6 or d10

The problem with this is that when you get to rolling more than one die, the probability distribution changes. 1d12 and 2d6 both offer a max of 12 (though the minimum is different - 1 vs. 2) but with 2d6 you're more likely to get an "average" roll, while with 1d12 you're equally likely to get any number. So the conversions don't really work precisely.
-Fiery Diamond

6. ## Re: d20 made into d6 or d10

Except that precision wasn't the goal here. Conversion was. If this is the closest we CAN get, then further precision isn't a worry.

7. ## Re: d20 made into d6 or d10

You may be interested in my 2d10 Variant. There is a thread on this page regarding it.

Feel free to critique or just have a look.

8. ## Re: d20 made into d6 or d10

Originally Posted by Fiery Diamond
The problem with this is that when you get to rolling more than one die, the probability distribution changes. 1d12 and 2d6 both offer a max of 12 (though the minimum is different - 1 vs. 2) but with 2d6 you're more likely to get an "average" roll, while with 1d12 you're equally likely to get any number. So the conversions don't really work precisely.
-Fiery Diamond
A d12 can be rolled using 2d6 with the exact same distribution if we map as:

Red d6 = 1,2,3 -> 0
Red d6 = 4,5,6 -> 6
Blue d6 = its value

Sum = 1 to 12 with equal probability

Some dice can only be approximated while others can be replicated exactly if we don't mind added complexity. I was bored, so here you go.

Example:
1d4 = 1d6 (re-roll 5's and 6's)
1d4 = Roll 2d6, Total = 4xMin + Max
If Total is 9 or lower, Value = 1
If Total between 10 and 13, Value = 2
If Total between 14 and 19, Value = 3
If Total is 20 or higher, Value = 4

Example:
1d5 requires re-rolls or is limited to approximation
1d5 = Roll 1d6, re-roll until you do not get a 6

Example:
1d6 = Roll 1d6

Example:
1d7 requires re-rolls or is limited to approximation
Roll 3d6, Total = 5xFirst + 8xSecond + 9xThird
Ranges are: -52,53-63,64-72,73-81,82-90,91-102,103+
Each range is within 0.0053 of 1/7th

Example:
1d8 = Roll 3d6, Total = 1xFirst + 2xSecond + 12xThird
Value = ((Total-16)/9) Rounded Up with a min of 1 and a max of 8
Ranges are: -25,26-34,25-43,44-52,53-61,62-70,71-79,80+

9. ## Re: d20 made into d6 or d10

It's possible to convert any given dice into a number of d6 and some math. That's not the point, because it's a pain. Seriously, who wants to roll 3d6/4 instead of just a d12?

If you aren't changing the probability curve, just use an internet roller instead of actual dice and make your life easier.

I find that changing the probability curve is also a pain, because weapon criticals have to be adjusted. Or not adjusted, as the case may be. In fact, you could change d20 into 2d10 pretty easily, and leave weapon criticals alone. That would make for a less spectacular battle, but if that's really a problem, double all critical ranges. If you are willing to go all this way to avoid a d20, though, there's something a mite wrong with you. If you don't have one, use the internet. If you don't have the internet, how are you reading this post?

If you have d20 phobia, then go ahead. I just use them.

10. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
Except that precision wasn't the goal here. Conversion was. If this is the closest we CAN get, then further precision isn't a worry.
Its a dice game. Tradition still holds favor, people love the feel of the dice in their hands.

Whether it be a d20, d10, or d6, people still like to roll them. Its fun.

11. ## Re: d20 made into d6 or d10

Originally Posted by Fiery Diamond
The problem with this is that when you get to rolling more than one die, the probability distribution changes. 1d12 and 2d6 both offer a max of 12 (though the minimum is different - 1 vs. 2) but with 2d6 you're more likely to get an "average" roll, while with 1d12 you're equally likely to get any number. So the conversions don't really work precisely.
-Fiery Diamond
Except that precision wasn't the goal here. Conversion was. If this is the closest we CAN get, then further precision isn't a worry.
I think you misunderstand.

Every number from 1-20 on a d20 has an equal chance of coming up (5%).
However rolling a 20 with two d10 is only 1%, meaning chances for a "nat 20" is lessened quite alot.

Now we could make alot of numeric stuff here (and if you ask, I'm sure you will get it), suffice it to say, as the number of dice increases the results clump up in the middle.

12. ## Re: d20 made into d6 or d10

I think the point is still being missed here. We're not trying to make it exactly like the d20 game, we're merely trying to convert it to a new dice system.

Remember, the new range in probable rolls is not a problem because all dice will be changed accordingly thus eliminating most inaccuracies. Anything else remaining is just because you converted to begin with.

13. ## Re: d20 made into d6 or d10

I like rolling a 'd20' with a d6 and a d10. One the d6, 1,2,3 = 0, 4,5,6 = 10, add that to the 10's roll.

I was thinking of using it in a D&D game, where crits are no longer confirmed (this is for 3.5 btw), but are automatic if you roll a 6 and a 10. Threat range would then decrease either dice (but not necessarily both simulateously) so a standard 19-20 threat range would crit on 5-6/10 or 6/9-10. A 15-20 threat range would crit on 4-6/8-10. Obviously, the d6 will 'min' at 4, though the d10 could go lower. If a weapon had a 12-20 threat range, it would crit on 4-6/5-10. Pretty impressive.

(plus this fits into the Topic, which made me think of it)

14. ## Re: d20 made into d6 or d10

Changing the D20 probability curve breaks low level play and makes high level play almost 100 percent predictable.

In fact, the 3d6 probability curve used by Champions/Hero System is the single biggest downfall of that system, it assures that opponents have to be very evenly matched or else no one can hit anyone else.

15. ## Re: d20 made into d6 or d10

*sigh*

Except the probability curve isn't being changed here. The villains will roll the same dice the heroes do. The EXACT same. No change. How is that not clear?

The conversion is only in the system itself to a d10 or d6, not change within the d20 system. How is this not getting through to all the rules lawyers out there who stress out about the probability curve? Yeesh.

16. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
*sigh*

Except the probability curve isn't being changed here. The villains will roll the same dice the heroes do. The EXACT same. No change. How is that not clear?

The conversion is only in the system itself to a d10 or d6, not change within the d20 system. How is this not getting through to all the rules lawyers out there who stress out about the probability curve? Yeesh.
I think it's completely clear to pretty much everyone. I think everyone assumed you meant that the same method would apply to both sides in a battle. What people are discussing is the impact on game play if you switch from the "traditional method" of attacking with a d20 or using 3d6.

To illustrate this point, an EXTREME example:
Replace the current dice rolling system with a system defined as: "all attacks hit and do exactly 100 points of damage." Obviously the probability curve (I kind of hate this term, BTW) is the same for both sides in a battle, is different from the SRD, and will have a major impact on game play (I REALLY want Improved Initiative! I REALLY hate fighting lots of low-level monsters!)

Using 3d6 for an attack is far less extreme, but since it ALTERS game play, it is important to understand when and how much. Understanding the "probability curve" is part of that dialog.

17. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
*sigh*

Except the probability curve isn't being changed here. The villains will roll the same dice the heroes do. The EXACT same. No change. How is that not clear?

The conversion is only in the system itself to a d10 or d6, not change within the d20 system. How is this not getting through to all the rules lawyers out there who stress out about the probability curve? Yeesh.
We understand that, it is not what we are commenting about.

Table on chances to roll a specific number (my first table, whee):
{table="head"] Roll a | 2d10 | 1d20
1 | 0 % | 5 %
2 | 1 % | 5 %
3 | 2 % | 5 %
4 | 3 % | 5 %
5 | 4 % | 5 %
6 | 5 % | 5 %
7 | 6 % | 5 %
8 | 7 % | 5 %
9 | 8 % | 5 %
10 | 9 % | 5 %
11 | 10 % | 5 %
12 | 9 % | 5 %
13 | 8 % | 5 %
14 | 7 % | 5 %
15 | 6 % | 5 %
16 | 5 % | 5 %
17 | 4 % | 5 %
18 | 3 % | 5 %
19 | 2 % | 5 %
20 | 1 % | 5 %
[/table]

You can see by the table above, the chances are not flat, as it is with the d20, infact when you roll more then one die at the same time, they tend to become "middle" numbers. My math may be alittle off, but the basic truth is there. That is what we mean by it changing the game.

Practical example. Your AC vs your opponents BAB is such that they need a 16 on a d20 to hit. that is hit on 16 & 17 & 18 & 19 & 20. chances of that is 25%.
Chances to hit 16 and above with 2d10 is 5% + 4% + 3% + 2% +1 % = 15%

Now I am not against this, as mentioned in the other thread about using 2d10 instead of d20 (but he mentioned it because of this effect, since it lessens the chance of crits and fumbles and generally evens out stuff), but it does change the game, for better or worse is up to you.

(math involved: d10 times d10 = 100 probabilities. Then I went though how many different ways the dice can form such numbers. a two can only be formed from a 1 and a 1 = 1 chance out of a hundred, or 1 %. There are two ways for a three, 1 +2 or 2+ 1 , therefore 2 % and so on. Atleast it totals 100% then I lost intrest in doublechecking.)

18. ## Re: d20 made into d6 or d10

Originally Posted by Khanderas
My math may be alittle off, but the basic truth is there. That is what we mean by it changing the game.
Close enough for government work.

For 2, 3, 4, ..., 10, 11, 12, ..., 18, 19, 20 the percentages are:

1%, 2%, 3%, ..., 9%, 10%, 9%, ..., 3%, 2%, 1%

(Edit: Hey! No fair editing it after I comment! Makes me think I'm going crazy.)

19. ## Re: d20 made into d6 or d10

Originally Posted by mroozee
Close enough for government work.

For 2, 3, 4, ..., 10, 11, 12, ..., 18, 19, 20 the percentages are:

1%, 2%, 3%, ..., 9%, 10%, 9%, ..., 3%, 2%, 1%

(Edit: Hey! No fair editing it after I comment! Makes me think I'm going crazy.)
Muahaha.
To be fair, I noticed a few mistakes ( went 1,2, 4, 5,6.... mistyped and skipped a 3) and edited before your post was done

20. ## Re: d20 made into d6 or d10

You see using 3d6 or 2d10 for D20 games throws it WAY out of whack even if both sides use the same dice.

At low level the players won't be able to hit their opponents, while at mid level the monsters won't be able to hit them, and at high level you might as well not even be rolling anymore.

Changing the dice also makes bonuses MUCH more valuable, and opposed rolls far more predictable.

It makes melee attacks less valuable and magic more powerful.

It changes EVERYTHING.

21. ## Re: d20 made into d6 or d10

You've all still missed the point. You AREN'T rolling 3d6 in place of a d20.

You're changing ALL dice to a d6 system. It is not longer the same system anymore.

All probabilities change equally (or very close to) since they're all being changed in the same fashion.

Your anal retentive analysis of the 3d6 variant for the d20 system is irrelevant in this thread since that wasn't the topic to begin with. The system itself was supposed to change not just add a simple variant.

22. ## Re: d20 made into d6 or d10

No, they're perfectly accurate. You still have a number of dice being rolled, which changes the standard distribution. 2d6/3 is a different algorithm than 1d4, and the probability of damage is different. This is exacerbated as you add die, no matter how many times you divide. What you propose doesn't work the way you want it to.

23. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
You've all still missed the point. You AREN'T rolling 3d6 in place of a d20.

You're changing ALL dice to a d6 system. It is not longer the same system anymore.

All probabilities change equally (or very close to) since they're all being changed in the same fashion.

Your anal retentive analysis of the 3d6 variant for the d20 system is irrelevant in this thread since that wasn't the topic to begin with. The system itself was supposed to change not just add a simple variant.
I cannot explain it more clearly. Suffice to say, "everyone" else, including me, says the system changes. The laws of probability says: you could be wrong here.

Note that, once again, I say I am not against the idea in principle, but it will change the game. The change may be better or it may be worse, but it will be different.
Edit: Re-read my table in a few post up and tell me that nothing will change.

24. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
The system itself was supposed to change not just add a simple variant.
Well, that's the whole point, isn't it? If you're changing the system itself, don't you want to have SOME idea of what those changes might be?

25. ## Re: d20 made into d6 or d10

Look, you've all over analyzed one thing and haven't been paying any attention to the real issue. Your probability curves are correct but they DON'T unbalance it because you would be making proper alterations on both sides. That's just good sense and I've said it again and again and have no idea why such a basic concept isn't getting through. Perhaps if I put it in visual numbers it would make more sense to the number crunchers and visual people:

Normal d20 system: 1d20 + bonuses vs. 10 + bonuses

What I suggested: 3d6 + bonus d6s vs. 3d6 + bonus d6s (or d10 system which is much different)

What you thought I said: 3d6 + flat bonuses vs. 10 + flat bonuses

That's wrong. That wasn't what I was expressing at all and had nothing to do with the original suggestion put forward. The altered probability isn't a problem because both sides of the equation (attack and defense, DC and save, damage and damage reduction, etc.) would be converted appropriately so that each side would have equal chance. Probability curves may change, but they don't make anything less or more fair so it doesn't matter.

The new probabilities don't throw anything out of whack except for luck rules which aren't a factor because they'd be excluded or also changed accordingly.

Now noted, an altered probability curve does change the game a bit (taking a slight amount of randomness out of it) but it doesn't make it unbalanced.

It is the BALANCE which was the goal, not equivalent probability with new dice.

26. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
Now noted, an altered probability curve does change the game a bit (taking a slight amount of randomness out of it) but it doesn't make it unbalanced.

It is the BALANCE which was the goal, not equivalent probability with new dice.
It seems like you agree with everyone else on these two points. Your goal may have been only to have something that is balanced, but everyone else is worried about how those game-changing probability alterations will look.

I think the problem is actually just semantics. The term balanced is over-loaded here. One reading suggests that a change to rules is balanced if it doesn't create an advantage for one side or the other. Another meaning results in a change to the rules being balanced if the basic game mechanic works about as well or better with the new addition.

Consider the following rules changes: "Everyone (PC's and NPC's including Monsters) has psionics", "All hit dice are maxed", "No one has energy drain", "Critical hits are instant kills", "Everyone's stats are rolled using 3d6; 4d6 take the best 3; or just summing 4d6" and "Movement is determined each round using some number of d6's"

All of these are "balanced" rules in the first sense of "fair to both sides" and would presumably pass your balancing test above. But some of these may not be "balanced" in the second sense of "workable within the rest of the d20 system".

27. ## Re: d20 made into d6 or d10

Originally Posted by arkanis
Normal d20 system: 1d20 + bonuses vs. 10 + bonuses

What I suggested: 3d6 + bonus d6s vs. 3d6 + bonus d6s (or d10 system which is much different)

What you thought I said: 3d6 + flat bonuses vs. 10 + flat bonuses
I should've mentioned that there's no real difference between opposed rolls and rolling against a target constant.

1d20 + flat bonuses vs. 10 + flat bonuses is equivalent to 1d20 vs. some constant

3d6 + flat bonuses vs. 10 + flat bonuses is equivalent to 3d6 vs. some constant

3d6 + bonus d6's vs. 3d6 + bonus d6's is equivalent to 6d6 + both bonus d6's vs. some constant

Assuming the right constants are picked, the only difference is the probability distribution created by the dice. But that's the whole point, really... what do the new dice options do to the rest of the game?

28. ## Re: d20 made into d6 or d10

Originally Posted by mroozee
I should've mentioned that there's no real difference between opposed rolls and rolling against a target constant.

1d20 + flat bonuses vs. 10 + flat bonuses is equivalent to 1d20 vs. some constant

3d6 + flat bonuses vs. 10 + flat bonuses is equivalent to 3d6 vs. some constant

3d6 + bonus d6's vs. 3d6 + bonus d6's is equivalent to 6d6 + both bonus d6's vs. some constant

Assuming the right constants are picked, the only difference is the probability distribution created by the dice. But that's the whole point, really... what do the new dice options do to the rest of the game?
Not entirely. Consider that the average of a d20 is 10.5. Even though each number has the same probability, there are more chances that a d20 roll will match or exceed 10 than fall below it on average (1-9 = failure, 10-20= success). See, the d20 system stats that you have to MATCH or exceed with a roll, not exceed. So they're not entirely equivalent, but close.

Originally Posted by mroozee
I think the problem is actually just semantics. The term balanced is over-loaded here. One reading suggests that a change to rules is balanced if it doesn't create an advantage for one side or the other. Another meaning results in a change to the rules being balanced if the basic game mechanic works about as well or better with the new addition.

Consider the following rules changes: "Everyone (PC's and NPC's including Monsters) has psionics", "All hit dice are maxed", "No one has energy drain", "Critical hits are instant kills", "Everyone's stats are rolled using 3d6; 4d6 take the best 3; or just summing 4d6" and "Movement is determined each round using some number of d6's"

All of these are "balanced" rules in the first sense of "fair to both sides" and would presumably pass your balancing test above. But some of these may not be "balanced" in the second sense of "workable within the rest of the d20 system".
Energy drain would work normally since it has nothing to do with the actual dice, merely the levels.

Hit point changes wouldn't be a problem as long as you changed all the damages accordingly as well.

Psionics, I've never used and never will they annoy me. If you want to go there that's your own business.

There may be less randomness in a d6 system but maximization is still just as good because the probability of rolling high/low is rare since you're normally pulled towards the middle.

Critical hits being instant kills since when? You mean vorpal? That was always broken. Just knock it down to where it belongs either by lowering the adjustment for it (since the probability of scoring a max roll is lowered).

I am personally against stat rolling, I think its unfair. I always stick to a point buy. However, if you stat roll here or in another system it doesn't really matter. There is no difference.

Movement determined by a number of d6s sounds like a great change. How do you suggest going about that? Divide the normal movements by 5 and that's the number of d6 rolled to move each time the creature attempts to outrun something? Taking 3 is okay for creatures with appropriate base speeds?

THIS is what we were supposed to be talking about. I'm glad we're back on topic.

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